Conformational study of poly-DeltaAbu peptides and construction of amphipathic nanostructure.

Generally, it is believed that alpha,beta-dehydroamino acid residues are most stable in the Z- form rather than in the E- form. In this study, it has been shown that poly-DeltaAbu exists in alternate Delta(E)Abu and Delta(Z)Abu form, with phi, psi values of approximately 0 degrees , 80 degrees and 35 degrees , 27 degrees for the E- and Z- forms, respectively, rather than the all Z- form. The conformational results for the peptides Ac-DeltaAbu(2)-NHMe and Ac-L/D-Ile-Delta(Z)Abu/Delta(E)Abu-NHMe suggest the incorporation of DeltaAbu in both the Z- and E- forms, which is consistent with the available observations in natural systems. Because of adoption of phi, psi values corresponding to the collagen type structure ( approximately -30 degrees , 120 degrees ) by Ile residue and with phi, psi values in the left-handed helical region for Delta(Z)Abu residue, the peptide Ac-(L-Ile-Delta(Z)Abu)(3)-NHMe adopts an amphipathic left-handed helical beta-sheet type structure. This structure is stabilized by network of hydrogen bonding, carbonyl-carbonyl, and CH-O interactions and can be exploited for the construction of antimicrobial peptides and nanomaterials.